Spatial variation of the current density. The contours a till b show the gradual current density variation for −3.3 ≤ x ≤ 3.3, −3.2 ≤ x ≤ 3.2 (a at t = 0.6 s, b at t = 1.14 s, c at t = 1.3 s, and d at t = 3.52 s). The significant variation in current density is shown in the last two plots for −2.7 ≤ x ≤ 2.7, −2.6 ≤ x ≤ 2.6 respectively at t = 6.02 s and t = 7.6 s. This shows that the place of current sheet generation is coincident with the heating place because of the ohmic dissipation.